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<div class="titlepage"><div><div><h5 class="title">
<a name="geometry.reference.algorithms.convex_hull.convex_hull_3_with_strategy"></a><a class="link" href="convex_hull_3_with_strategy.html" title="convex_hull (with strategy)">convex_hull
          (with strategy)</a>
</h5></div></div></div>
<p>
            <a class="indexterm" name="idm45246446663072"></a>
Calculates the convex hull of a geometry using the specified strategy.
          </p>
<h6>
<a name="geometry.reference.algorithms.convex_hull.convex_hull_3_with_strategy.h0"></a>
            <span class="phrase"><a name="geometry.reference.algorithms.convex_hull.convex_hull_3_with_strategy.description"></a></span><a class="link" href="convex_hull_3_with_strategy.html#geometry.reference.algorithms.convex_hull.convex_hull_3_with_strategy.description">Description</a>
          </h6>
<p>
            The free function convex_hull calculates the convex hull of a geometry
            using the specified strategy.
          </p>
<h6>
<a name="geometry.reference.algorithms.convex_hull.convex_hull_3_with_strategy.h1"></a>
            <span class="phrase"><a name="geometry.reference.algorithms.convex_hull.convex_hull_3_with_strategy.synopsis"></a></span><a class="link" href="convex_hull_3_with_strategy.html#geometry.reference.algorithms.convex_hull.convex_hull_3_with_strategy.synopsis">Synopsis</a>
          </h6>
<p>
</p>
<pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Geometry</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">OutputGeometry</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Strategy</span><span class="special">&gt;</span>
<span class="keyword">void</span> <span class="identifier">convex_hull</span><span class="special">(</span><span class="identifier">Geometry</span> <span class="keyword">const</span> <span class="special">&amp;</span> <span class="identifier">geometry</span><span class="special">,</span> <span class="identifier">OutputGeometry</span> <span class="special">&amp;</span> <span class="identifier">out</span><span class="special">,</span> <span class="identifier">Strategy</span> <span class="keyword">const</span> <span class="special">&amp;</span> <span class="identifier">strategy</span><span class="special">)</span></pre>
<p>
          </p>
<h6>
<a name="geometry.reference.algorithms.convex_hull.convex_hull_3_with_strategy.h2"></a>
            <span class="phrase"><a name="geometry.reference.algorithms.convex_hull.convex_hull_3_with_strategy.parameters"></a></span><a class="link" href="convex_hull_3_with_strategy.html#geometry.reference.algorithms.convex_hull.convex_hull_3_with_strategy.parameters">Parameters</a>
          </h6>
<div class="informaltable"><table class="table">
<colgroup>
<col>
<col>
<col>
<col>
</colgroup>
<thead><tr>
<th>
                    <p>
                      Type
                    </p>
                  </th>
<th>
                    <p>
                      Concept
                    </p>
                  </th>
<th>
                    <p>
                      Name
                    </p>
                  </th>
<th>
                    <p>
                      Description
                    </p>
                  </th>
</tr></thead>
<tbody>
<tr>
<td>
                    <p>
                      Geometry const &amp;
                    </p>
                  </td>
<td>
                    <p>
                      the input geometry type
                    </p>
                  </td>
<td>
                    <p>
                      geometry
                    </p>
                  </td>
<td>
                    <p>
                      A model of the specified concept, input geometry
                    </p>
                  </td>
</tr>
<tr>
<td>
                    <p>
                      OutputGeometry &amp;
                    </p>
                  </td>
<td>
                    <p>
                      the output geometry type
                    </p>
                  </td>
<td>
                    <p>
                      out
                    </p>
                  </td>
<td>
                    <p>
                      A model of the specified concept which is set to the convex
                      hull
                    </p>
                  </td>
</tr>
<tr>
<td>
                    <p>
                      Strategy const &amp;
                    </p>
                  </td>
<td>
                    <p>
                      the strategy type
                    </p>
                  </td>
<td>
                    <p>
                      strategy
                    </p>
                  </td>
<td>
                    <p>
                      The strategy which will be used for area calculations
                    </p>
                  </td>
</tr>
</tbody>
</table></div>
<h6>
<a name="geometry.reference.algorithms.convex_hull.convex_hull_3_with_strategy.h3"></a>
            <span class="phrase"><a name="geometry.reference.algorithms.convex_hull.convex_hull_3_with_strategy.header"></a></span><a class="link" href="convex_hull_3_with_strategy.html#geometry.reference.algorithms.convex_hull.convex_hull_3_with_strategy.header">Header</a>
          </h6>
<p>
            Either
          </p>
<p>
            <code class="computeroutput"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">geometry</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span></code>
          </p>
<p>
            Or
          </p>
<p>
            <code class="computeroutput"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">geometry</span><span class="special">/</span><span class="identifier">algorithms</span><span class="special">/</span><span class="identifier">convex_hull</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span></code>
          </p>
<h6>
<a name="geometry.reference.algorithms.convex_hull.convex_hull_3_with_strategy.h4"></a>
            <span class="phrase"><a name="geometry.reference.algorithms.convex_hull.convex_hull_3_with_strategy.conformance"></a></span><a class="link" href="convex_hull_3_with_strategy.html#geometry.reference.algorithms.convex_hull.convex_hull_3_with_strategy.conformance">Conformance</a>
          </h6>
<p>
            The function convex_hull implements function ConvexHull() from the <a href="http://www.opengeospatial.org/standards/sfa" target="_top">OGC Simple Feature
            Specification</a>.
          </p>
<h6>
<a name="geometry.reference.algorithms.convex_hull.convex_hull_3_with_strategy.h5"></a>
            <span class="phrase"><a name="geometry.reference.algorithms.convex_hull.convex_hull_3_with_strategy.supported_geometries"></a></span><a class="link" href="convex_hull_3_with_strategy.html#geometry.reference.algorithms.convex_hull.convex_hull_3_with_strategy.supported_geometries">Supported
            geometries</a>
          </h6>
<div class="informaltable"><table class="table">
<colgroup>
<col>
<col>
</colgroup>
<thead><tr>
<th>
                    <p>
                      Geometry
                    </p>
                  </th>
<th>
                    <p>
                      Status
                    </p>
                  </th>
</tr></thead>
<tbody>
<tr>
<td>
                    <p>
                      Point
                    </p>
                  </td>
<td>
                    <p>
                      <span class="inlinemediaobject"><img src="../../../../img/ok.png" alt="ok"></span>
                    </p>
                  </td>
</tr>
<tr>
<td>
                    <p>
                      Segment
                    </p>
                  </td>
<td>
                    <p>
                      <span class="inlinemediaobject"><img src="../../../../img/ok.png" alt="ok"></span>
                    </p>
                  </td>
</tr>
<tr>
<td>
                    <p>
                      Box
                    </p>
                  </td>
<td>
                    <p>
                      <span class="inlinemediaobject"><img src="../../../../img/ok.png" alt="ok"></span>
                    </p>
                  </td>
</tr>
<tr>
<td>
                    <p>
                      Linestring
                    </p>
                  </td>
<td>
                    <p>
                      <span class="inlinemediaobject"><img src="../../../../img/ok.png" alt="ok"></span>
                    </p>
                  </td>
</tr>
<tr>
<td>
                    <p>
                      Ring
                    </p>
                  </td>
<td>
                    <p>
                      <span class="inlinemediaobject"><img src="../../../../img/ok.png" alt="ok"></span>
                    </p>
                  </td>
</tr>
<tr>
<td>
                    <p>
                      Polygon
                    </p>
                  </td>
<td>
                    <p>
                      <span class="inlinemediaobject"><img src="../../../../img/ok.png" alt="ok"></span>
                    </p>
                  </td>
</tr>
<tr>
<td>
                    <p>
                      MultiPoint
                    </p>
                  </td>
<td>
                    <p>
                      <span class="inlinemediaobject"><img src="../../../../img/ok.png" alt="ok"></span>
                    </p>
                  </td>
</tr>
<tr>
<td>
                    <p>
                      MultiLinestring
                    </p>
                  </td>
<td>
                    <p>
                      <span class="inlinemediaobject"><img src="../../../../img/ok.png" alt="ok"></span>
                    </p>
                  </td>
</tr>
<tr>
<td>
                    <p>
                      MultiPolygon
                    </p>
                  </td>
<td>
                    <p>
                      <span class="inlinemediaobject"><img src="../../../../img/ok.png" alt="ok"></span>
                    </p>
                  </td>
</tr>
</tbody>
</table></div>
<h6>
<a name="geometry.reference.algorithms.convex_hull.convex_hull_3_with_strategy.h6"></a>
            <span class="phrase"><a name="geometry.reference.algorithms.convex_hull.convex_hull_3_with_strategy.complexity"></a></span><a class="link" href="convex_hull_3_with_strategy.html#geometry.reference.algorithms.convex_hull.convex_hull_3_with_strategy.complexity">Complexity</a>
          </h6>
<p>
            Linearithmic
          </p>
<h6>
<a name="geometry.reference.algorithms.convex_hull.convex_hull_3_with_strategy.h7"></a>
            <span class="phrase"><a name="geometry.reference.algorithms.convex_hull.convex_hull_3_with_strategy.example"></a></span><a class="link" href="convex_hull_3_with_strategy.html#geometry.reference.algorithms.convex_hull.convex_hull_3_with_strategy.example">Example</a>
          </h6>
<p>
            Shows how to generate the convex_hull of a geometry
          </p>
<p>
</p>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">iostream</span><span class="special">&gt;</span>

<span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">geometry</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
<span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">geometry</span><span class="special">/</span><span class="identifier">geometries</span><span class="special">/</span><span class="identifier">polygon</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
<span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">geometry</span><span class="special">/</span><span class="identifier">geometries</span><span class="special">/</span><span class="identifier">adapted</span><span class="special">/</span><span class="identifier">boost_tuple</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>

<span class="identifier">BOOST_GEOMETRY_REGISTER_BOOST_TUPLE_CS</span><span class="special">(</span><span class="identifier">cs</span><span class="special">::</span><span class="identifier">cartesian</span><span class="special">)</span>


<span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span>
<span class="special">{</span>
    <span class="keyword">typedef</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">tuple</span><span class="special">&lt;</span><span class="keyword">double</span><span class="special">,</span> <span class="keyword">double</span><span class="special">&gt;</span> <span class="identifier">point</span><span class="special">;</span>
    <span class="keyword">typedef</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">geometry</span><span class="special">::</span><span class="identifier">model</span><span class="special">::</span><span class="identifier">polygon</span><span class="special">&lt;</span><span class="identifier">point</span><span class="special">&gt;</span> <span class="identifier">polygon</span><span class="special">;</span>

    <span class="identifier">polygon</span> <span class="identifier">poly</span><span class="special">;</span>
    <span class="identifier">boost</span><span class="special">::</span><span class="identifier">geometry</span><span class="special">::</span><span class="identifier">read_wkt</span><span class="special">(</span><span class="string">"polygon((2.0 1.3, 2.4 1.7, 2.8 1.8, 3.4 1.2, 3.7 1.6,3.4 2.0, 4.1 3.0"</span>
        <span class="string">", 5.3 2.6, 5.4 1.2, 4.9 0.8, 2.9 0.7,2.0 1.3))"</span><span class="special">,</span> <span class="identifier">poly</span><span class="special">);</span>

    <span class="identifier">polygon</span> <span class="identifier">hull</span><span class="special">;</span>
    <span class="identifier">boost</span><span class="special">::</span><span class="identifier">geometry</span><span class="special">::</span><span class="identifier">convex_hull</span><span class="special">(</span><span class="identifier">poly</span><span class="special">,</span> <span class="identifier">hull</span><span class="special">);</span>

    <span class="keyword">using</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">geometry</span><span class="special">::</span><span class="identifier">dsv</span><span class="special">;</span>
    <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span>
        <span class="special">&lt;&lt;</span> <span class="string">"polygon: "</span> <span class="special">&lt;&lt;</span> <span class="identifier">dsv</span><span class="special">(</span><span class="identifier">poly</span><span class="special">)</span> <span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span>
        <span class="special">&lt;&lt;</span> <span class="string">"hull: "</span> <span class="special">&lt;&lt;</span> <span class="identifier">dsv</span><span class="special">(</span><span class="identifier">hull</span><span class="special">)</span> <span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span>
        <span class="special">;</span>


    <span class="keyword">return</span> <span class="number">0</span><span class="special">;</span>
<span class="special">}</span>
</pre>
<p>
          </p>
<p>
            Output:
          </p>
<pre class="programlisting">polygon: (((2, 1.3), (2.4, 1.7), (2.8, 1.8), (3.4, 1.2), (3.7, 1.6), (3.4, 2), (4.1, 3), (5.3, 2.6), (5.4, 1.2), (4.9, 0.8), (2.9, 0.7), (2, 1.3)))
hull: (((2, 1.3), (2.4, 1.7), (4.1, 3), (5.3, 2.6), (5.4, 1.2), (4.9, 0.8), (2.9, 0.7), (2, 1.3)))

<img src="../../../../img/algorithms/convex_hull.png" alt="convex_hull">
</pre>
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<td align="right"><div class="copyright-footer">Copyright © 2009-2021 Barend Gehrels,
      Bruno Lalande, Mateusz Loskot, Adam Wulkiewicz, Oracle and/or its affiliates<p>
        Distributed under the Boost Software License, Version 1.0. (See accompanying
        file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
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